Simplify the following expression: $x = \dfrac{20p - 40}{8p + 4}$ You can assume $p \neq 0$.
Answer: Find the greatest common factor of the numerator and denominator. The numerator can be factored: $20p - 40 = (2\cdot2\cdot5 \cdot p) - (2\cdot2\cdot2\cdot5)$ The denominator can be factored: $8p + 4 = (2\cdot2\cdot2 \cdot p) + (2\cdot2)$ The greatest common factor of all the terms is $4$ Factoring out $4$ gives us: $x = \dfrac{(4)(5p - 10)}{(4)(2p + 1)}$ Dividing both the numerator and denominator by $4$ gives: $x = \dfrac{5p - 10}{2p + 1}$